This invention relates to a brake servo booster, primarily for use in a vehicle braking system and of the general kind comprising a housing divided into a pair of chambers by a movable partition which includes a diaphragm secured in sealed manner to the housing, the partition being operatively connected to a force output member for the transmission of a power assistance force to a brake master cylinder, a support member extending through the partition and serving to connect the booster, in use, to a fixed support, and a protective boot extending longitudinally of the support member and surrounding an external surface thereof, the boot being connected at its end regions respectively to the support member and to the partition.
Examples of an arrangement of this general kind are illustrated in our British Patent No. 2093136 in which a protective boot has one of its end regions secured directly to the partition diaphragm. While this produces a satisfactory operational arrangement, difficulty can be experienced in assembling the boot on to the diaphragm, largely due to the nature of the material employed for these components, being usually rubber or plastics, for example, in practice, and the shapes of their interengaging parts which cannot readily be manipulated on an assembly line.